slepc-3.21.1 2024-04-26
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Computes y = beta*y + alpha*X*q, where y is the j-th column of X.


#include "slepcbv.h" 
PetscErrorCode BVMultColumn(BV X,PetscScalar alpha,PetscScalar beta,PetscInt j,PetscScalar *q)
Logically Collective

Input Parameters

X  - a basis vectors object
alpha  - first scalar
beta  - second scalar
j  - the column index
q  - an array of scalars


This operation is equivalent to BVMultVec() but it uses column j of X rather than taking a Vec as an argument. The number of active columns of X is set to j before the computation, and restored afterwards. If X has leading columns specified, then these columns do not participate in the computation. Therefore, the length of array q must be equal to j minus the number of leading columns.

Developer Notes

If q is NULL, then the coefficients are taken from position nc+l of the internal buffer vector, see BVGetBufferVec().

See Also

BVMult(), BVMultVec(), BVMultInPlace(), BVSetActiveColumns()





Index of all BV routines
Table of Contents for all manual pages
Index of all manual pages